Revisiting the Economic Impacts of Eimeria and Its Control in European Intensive Broiler Systems With a Recursive Modeling Approach

Abstract

Ionophore compounds active against Eimeria species are widely used in intensive broiler systems and have formed the backbone of coccidiosis control for almost 50 years. Producers, however, are under pressure to reduce ionophore use due to consumer concerns over antimicrobial usage in food animals, and antimicrobial resistance. Moreover, current vaccines against Eimeria are commonly considered to be less cost-effective in intensive broiler systems, especially in Europe where attenuated live vaccines are used. An economic assessment of the impact of Eimeria and the disease coccidiosis, including the cost implications of different efficacies of control, is therefore timely to provide evidence for industry and policy development. A mechanistic model of broiler production under varying infection and control states was used to construct a dataset from which system productivity can be measured. Coccidiosis impact increased rapidly as control efficacy decreased. In the total absence of control, median impact was found to maximize at between €2.55 and €2.97 in lost production per meter squared of broiler house over a 33 day growing period. Coccidiosis remains a major risk to intensive broiler systems and the model developed allows investigation of issues related to coccidiosis control, antimicrobial use and the development of antimicrobial resistance.

Keywords: Eimeria; broiler; coccidiosis; disease control; economics; impact; model.

Figure 1

Lifecycle of Eimeria species. Life cycle stages are denoted by x_n. Rate of advancement between stages is determined by coefficient a_n. The time lag between each stage is represented by t_n. Removal of pathogen from the system is indicated by m_n. Immunity generation is indicated by I. Eimeria tenella has one fewer lifecycle stages, and proceeds directly from x₅ to x₇.

Figure 2

Source data and recursive growth model fit for bird weight over days of production, estimated from feed intake, feed schedule, and energy conversion models.

Figure 3

Pathogen influence on reduction in metabolizable energy (ME) absorption from the gut, lines show the mean and 95% CI of model prediction, with source data indicated by point: (A) Eimeria acervulina, (B) Eimeria maxima, (C) Eimeria tenella.

Figure 4

Impact of multiple Eimeria species (E. acervulina, maxima, tenella) on average daily weight gain in simulated infected broiler flocks, with 95% distribution, with and without control.

Figure 5

Mean within flock protective immunity against Eimeria species (A) in the absence of control measures; and (B) with control of Eimeria at 75% efficacy.

Figure 6

Impact of increasing control efficacy and variable infection pressure on efficiency of feed conversion in 350 simulated commercial broiler flocks.

Figure 7

Impact of Eimeria infection on producer margin over feed costs (€/m²) under increasing levels of control efficacy and infection pressure in 350 simulated flocks.